What linux shell command returns a part of a string?

Question

I want to find a linux command that can return a part of the string. In most programming languages, it's the substr() function. Does bash have any command that can be used for this purpose. I want to be able to do something like this... substr "abcdefg" 2 3 - prints 'cde'

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Subsequent similar question:

• http://stackoverflow.com/questions/428109/extract-substring-in-bash

Answer 1

From the bash manpage:

${parameter:offset}
${parameter:offset:length}
        Substring  Expansion.   Expands  to  up  to length characters of
        parameter starting at the character  specified  by  offset.

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Or, if you are not sure of having bash, consider using cut.

Answer 2

In bash you can try this:

stringZ=abcABC123ABCabc
#       0123456789.....
#       0-based indexing.

echo ${stringZ:0:2} # prints ab

More samples in The Linux Documentation Project

Answer 3

${string:position:length}

Answer 4

If you are looking for a shell utility to do something like that, you can use the cut command.

To take your example, try:

echo "abcdefg" | cut -c3-5

Where -cN-M tells the cut command to return columns N to M, inclusive.

Answer 5

expr(1) has a substr subcommand:

expr substr string position length

This may be useful if you don't have bash (perhaps embedded Linux) and you don't want the extra "echo" process you need to use cut(1).